In cutting inserts for grooving process and copying process (hereinafter referred to as “inserts” in some cases), various considerations about the shape of a rake surface of the insert have conventionally been made, for example, in order to smoothly discharge generated chips (for example, refer to Japanese Unexamined Patent Publication No. 5-253709).
However, in the insert described in Japanese Unexamined Patent Publication No. 5-253709, as shown in FIG. 5, a protruded part 11 as a connection part between adjacent recessed parts 8 has a relatively large width in the vicinity of a cutting edge 6, and the width thereof is kept constant or decreased as the protruded part 11 goes inward from the vicinity of the cutting edge 6. Accordingly, there is a risk that cutting resistance during cutting is increased by the wide protruded part 11 in the vicinity of the cutting edge 6, thus failing to smoothly discharge the chips.
Also in the insert described in Japanese Unexamined Patent Publication No. 5-253709, as shown in FIGS. 5 and 9, the recessed parts 8 and a protrusion 10 are smoothly continuous with each other as going inward from the cutting edge 6. Thus, for example, there is a risk that the chips generated by the cutting edge 6 cannot smoothly be discharged.
Hence, there is a need to improve discharge performance for the chips generated by the cutting edge.